// acwing.901滑雪 https://www.acwing.com/problem/content/903/
#include<bits/stdc++.h>
using namespace std;

const int N = 310;
int n, m;
int h[N][N];
int f[N][N];

int dx[4] = {0, 1, 0, -1}, dy[4] = {-1, 0, 1, 0};
int dp(int x, int y)
{
    int &v = f[x][y];
    if (v != -1) return v;
    
    v = 1;
    for (int i = 0; i < 4; i ++ )
    {
        int a = x + dx[i], b = y + dy[i];
        if (a >= 1 && a <= n && b >= 1 && b <= m && h[a][b] < h[x][y])
            v = max(v, dp(a, b) + 1);
    }
    
    return v;
}

int main()
{
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i ++ ) 
        for (int j = 1; j <= m; j ++ )
            scanf("%d", &h[i][j]);
            
    memset(f, -1, sizeof f);
    
    int res = 0;
    for (int i = 1; i <= n; i ++ )
        for (int j = 1; j <= m; j ++ )
            res = max(res, dp(i, j));
    
    printf("%d\n", res);
    return 0;
}